The digital image is composed of discrete elements called pixels, and “pixel pitch”, similar to “dot pitch” of a CRT display, is the physical distance between two adjacent pixels in a LCD display device and is one of the critical factors affecting image quality.
As known, the optimal viewing comfort can be achieved by making the width of screen occupy 45 degrees of visual angle. Table 1 shows the calculation results of visual angle per pixel for the display devices with different sizes. As clearly shown in Table 1, the visual angle per pixel is decided by the display resolution, irrespective of the size of the display device.
TABLE 1PixelViewingSize(Inch)Width(mm)Height(mm)Res.(W)Res.(H)Pitch(mm)Distance(cm)Degree/Pitch1530422810247680.29736.69590.046417337.9270128010240.26440.7880.037119376.3301.1128010240.29445.42330.037119.0 W408.2255.114409000.28349.27390.032920.1 W433.4270.9168010500.25852.31580.028322.0 W473.8296.1168010500.28257.19250.028324.0 W518.5324192012000.2762.58830.024725.5 W550.1343.8192012000.28766.40270.024827.5 W593.3370.8192012000.30971.61740.024730.0 W641.3400.8256016000.250577.41150.0185
Generally, the website designer usually constructs web pages/sites with 800×600 or 1024×768 resolution, and under these resolution, characters consisted of the same number of dots will exhibit different pitch scales when being displayed on different display screens of different sizes, which may degrade the visibility of the content of the display.
Besides the physical viewing condition, the viewer's preference has an effect on the perceived quality of an image or a video. A user can change the magnification level by setting display properties. Various types of display screen magnification and zoom functionalities are provided in most of today's computer systems, which mainly use software to zoom the image or the video. However, adjusting preferred setting on the display devices is inconvenient for the user because a number of system interactions with the user are required and such interactions may be burdensome and time-consuming.
Consequently, it is necessary to provide a display system capable of automatically varying scale of displayed content to facilitate user viewing.